Thrust plate for butterfly valve

ABSTRACT

A thrust plate for a butterfly valve includes a thrust plate body that defines a recess that extends between a bottom thrust surface, side walls, and an open top. There is a nickel-based or cobalt-based wear-resistant coating located on the bottom thrust surface. The wear-resistant coating is harder than the thrust plate body.

CROSS REFERENCE TO RELATED APPLICATION

This application is a continuation U.S. application Ser. No. 13/007,850filed on Jan. 17, 2011.

BACKGROUND

This disclosure relates to a butterfly valve having a wear-resistantcoating.

Butterfly valves are known and used to control air flow. A typicalbutterfly valve includes a housing that defines an air flow passage. Ashaft is mounted in a housing and supports a butterfly disk. An actuatorrotates the shaft to selectively open or close the butterfly disk tocontrol the air flow through the passage in the housing.

SUMMARY

A thrust plate for a butterfly valve according to an example of thepresent disclosure includes a thrust plate body that defines a recessthat extends between a bottom thrust surface, side walls, and an opentop. A nickel-based or cobalt-based wear-resistant coating is located onthe bottom thrust surface. The wear-resistant coating is harder than thethrust plate body.

In a further embodiment of any of the foregoing embodiments, thewear-resistant coating is a nickel-based alloy.

In a further embodiment of any of the foregoing embodiments, thewear-resistant coating includes chromium boride.

In a further embodiment of any of the foregoing embodiments, thewear-resistant coating includes chromium carbide.

In a further embodiment of any of the foregoing embodiments, the thrustplate body is stainless steel.

In a further embodiment of any of the foregoing embodiments, a ratio ofa hardness of the wear-resistant coating to a hardness of the stainlesssteel is at least 2.3.

In a further embodiment of any of the foregoing embodiments, the recessdefines a recess diameter (RD1) and the wear-resistant coating definesan average coating thickness (CT), and ratio RD1/CT is between 33.2 and56.67.

In a further embodiment of any of the foregoing embodiments, the recessdefines a recess depth (RD2) and the wear-resistant coating defines anaverage coating thickness (CT), and a ratio RD2/CT is between 5 and10.33.

In a further embodiment of any of the foregoing embodiments, the thrustplate body, with the exception of the bottom thrust surface, is free ofthe wear-resistant coating.

In a further embodiment of any of the foregoing embodiments, the thrustplate body is a material selected from a group consisting ofnickel-based alloy, cobalt-based alloy and steel, and the wear-resistantcoating is a nickel-based alloy.

A butterfly valve according to an example of the present disclosureincludes a valve housing that defines a flow passage there through, ashaft that extends in the valve housing, and gas a butterfly diskmounted thereon within the flow passage. A thrust plate includes athrust plate body that defines a recess that receives an end of theshaft. The recess extends between a bottom thrust surface, side walls,and an open top. A wear-resistant coating is located on the bottomthrust surface.

In a further embodiment of any of the foregoing embodiments, thewear-resistant coating consists essentially of 0.5-1.0 wt. % carbon,12-18 wt. % chromium, 2.5-4.5 wt. % boron, 3.5-5.5 wt. % silicon,3.5-5.5 wt. % iron, up to 0.2 wt. % cobalt, and a remainder of nickel

In a further embodiment of any of the foregoing embodiments, the thrustplate body is stainless steel.

In a further embodiment of any of the foregoing embodiments, a ratio ofa hardness of the wear-resistant coating to a hardness of the stainlesssteel is at least 2.3.

In a further embodiment of any of the foregoing embodiments, the recessdefines a recess diameter (RD1) and the wear-resistant coating definesan average coating thickness (CT), and ratio RD1/CT is between 33.2 and56.67.

In a further embodiment of any of the foregoing embodiments, the recessdefines a recess depth (RD2) and the wear-resistant coating defines anaverage coating thickness (CT), and a ratio RD2/CT is between 5 and10.33.

In a further embodiment of any of the foregoing embodiments, the thrustplate body, with the exception of the bottom thrust surface, is free ofthe wear-resistant coating.

In a further embodiment of any of the foregoing embodiments, the flowpassage defines a central axis, and a long axis of the shaft isnon-perpendicular to the central axis.

In a further embodiment of any of the foregoing embodiments, the recessdefines a recess diameter (RD1) and a recess depth (RD2) and thewear-resistant coating defines an average coating thickness (CT) suchthat a ratio RD1/CT is between 33.2 and 56.67 and a ratio RD2/CT isbetween 5 and 10.33.

A method of installing a thrust plate on a butterfly valve according toan example of the present disclosure includes securing a thrust plate toa valve housing that defines a flow passage there through such that anend of a shaft, which extends within the valve housing and includes abutterfly disk mounted thereon, is received into a recess of the thrustplate body. The recess extends between a bottom thrust surface, sidewalls and an open top. The bottom thrust surface includes awear-resistant coating thereon.

BRIEF DESCRIPTION OF THE DRAWINGS

The various features and advantages of the disclosed examples willbecome apparent to those skilled in the art from the following detaileddescription. The drawings that accompany the detailed description can bebriefly described as follows.

FIG. 1 illustrates an example aircraft that includes an air managementsystem.

FIG. 2 is an isolated view of a thrust plate within a valve of the airmanagement system.

FIG. 3 is another view of the thrust plate of FIG. 2.

FIG. 4 is a cross-sectional view of the thrust plate shown in FIG. 3.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

FIG. 1 illustrates selected portions of an example aircraft 10 thatincludes an air management system 12 mounted to a support 14 within theaircraft 10. The example air management system 12 includes a conduit 16that defines a flow passage 18 along a central axis A for air flow.

A valve assembly 20 controls air flow through the flow passage 18. Thevalve assembly 20 includes a valve housing 21 that defines at least aportion of the flow passage 18. A butterfly disk 22 is mounted on ashaft 24 within the valve housing 21, and an actuator 26 (e.g., apneumatic actuator) is operatively connected to the shaft 24 to move thebutterfly disk 22 about a long axis 28 of the shaft 24. The shaft 24includes an axial end 30 that is supported by a thrust plate 32. Thethrust plate 32 limits movement of the shaft along the long axis 28.

The air management system 12 is required to operate at elevatedtemperatures, such as 1200° F. (649° C.), and high vibration levels withlittle or no lubrication. Furthermore, the long axis 28 of the shaft 24is non-perpendicular to the central axis A and thereby produces a thrustload along the long axis 28 (indicated at 34). As will be described, theexample thrust plate 32 includes a wear-resistant coating 40 at theinterface with the axial end 30 of the shaft 24, to facilitate areduction in friction and wear from the thrust load 34 that the shaft 24exerts on the thrust plate 32.

Referring to FIGS. 2-4, the thrust plate 32 is formed from a thrustplate body 42 that defines a recess 44 therein. The recess 44 generallyextends between a bottom thrust surface 46, side walls 48 and an opentop 50. As shown in FIG. 1, the axial end 30 of the shaft 24 is receivedinto the recess 44 such that the axial end 30 contacts the bottom thrustsurface 46. In that regard, the thrust plate body 42 includes awear-resistant coating 40 on the bottom thrust surface 46 to resist wearbetween the thrust plate body 42 and the shaft 24 from the thrust load34 produced during operation of the valve assembly 20.

In the example shown in FIG. 4, the recess 44 defines a recess diameter(RD1) and a recess depth (RD2). The recess depth extends between thebottom thrust surface 46 and a plane that is defined by a ledge or step51 in the recess 44. In this example, the recess depth is taken from thelower portion of the step 51 at the location where the recess 44 narrowsto the recess diameter.

The wear-resistant coating 40 also defines an average coating thickness(CT). For instance, the average coating thickness may be an average ofthicknesses taken at selected locations across the wear-resistantcoating 40.

In embodiments, the recess diameter (RD1) is 0.830-0.850 inches and maynominally be 0.840 inches. The recess depth (RD2) is 0.125-0.155 inchesand may nominally be 0.140 inches. The coating thickness (CT) is0.015-0.025 inches and may nominally be 0.020 inches.

In embodiments, the thrust plate 32 and wear-resistant coating 40 aredesigned with a ratio of RD1/CT that is between 33.2 and 56.67. In afurther embodiment, the thrust plate 32 and wear-resistant coating 40are also designed with a ratio of RD2/CT that is between 5 and 10.33.The selected ratios ensure that the wear-resistant coating 40 has asufficient thickness to provide wear-resistance for a given recess sizeand also ensure that the wear-resistant coating 40 provides the properaxial positioning of the shaft 24.

The wear-resistant coating 40 is designed to be harder than the materialof the thrust plate body 42 to thereby provide the wear-resistance. Asan example, the material of the thrust plate body 42 may be anaustenitic or precipitation hardened stainless steel. In otherembodiments, the material of the thrust plate body 42 may be anickel-based alloy, a cobalt-based alloy or steel. The nickel-basedalloy may be Inconel® 625 or 718, the cobalt-based alloy may be Haynes®25, Stellite® 31 or Stellite® 60. The element that is the base elementof the alloy refers to that element being present in a greater amountthan any other element in the composition.

The material of the wear-resistant coating 40 is designed to protect thethrust plate body 42. In embodiments, the wear-resistant coating 40 is anickel-based alloy or a cobalt-based alloy that is harder than thematerial of the thrust plate body 42. As an example, the nickel-basedalloy may have a composition that essentially includes 0.5-1.0 wt. %carbon, 12-18 wt. % chromium, 2.5-4.5 wt. % boron, 3.5-5.5 wt. %silicon, 3.5-5.5 wt. % iron, up to 0.2 wt. % cobalt, and a remainder ofnickel. The alloys may include impurities that do not affect theproperties of the material or elements that are unmeasured orundetectable in the material.

The nickel-based alloy of the wear-resistant coating 40 may include hardcompounds or phases that contribute to the high hardness of thewear-resistant coating 40. For instance, the hard compounds or phasesmay include chromium boride, chromium carbide, or both. Thewear-resistant coating 40 may additionally include silicides. Theborides, carbides, and/or silicides may be formed between the elementsof the composition of the wear-resistant coating 40.

The flow passage 18 of the valve assembly 20 defines a diameter (D_(p))(FIG. 1) and the shaft 24 contacts the wear-resistant coating 40 over aninterface area (CA) (FIG. 4). A ratio D_(p)/CA determines the amount ofthrust load 34 on the bottom thrust surface 46 of the thrust plate 32.In embodiments, the ratio D_(p)/CA is between 8 and 12.

The relative hardness of the wear-resistant coating 40 in comparison tothe hardness of the material of the thrust plate body 42 is designed toprovide a desired level of wear-resistance. For instance, a ratio of thehardness of the wear-resistant coating 40 to the hardness of thematerial of the thrust plate body 42 is at least 2.3. In a furtherexample, the hardness of the wear-resistant coating 40 may be at least55 HRC and the hardness of the material of the thrust plate body 42 maybe a maximum of 23 HRC. The wear-resistant coating 40 thereby provides asufficient level of wear-resistance with regard to the thrust load 34that is expected from the given ratio D_(p)/CA.

The wear-resistant coating 40 resists wear such that during theoperation of the valve assembly 20, the shaft 24 and butterfly disk 22maintain a concentric position within the flow passage 18. The shaft 24and butterfly disk 22 therefore do not shift position due to thrustplate 32 wear that could otherwise lead to binding and hindering ofvalve operation. That is, the absence of the wear-resistant coating 40may otherwise lead to wear of the shaft 24 and/or of the bottom thrustsurface 46 under the given thrust load 34 such that the shaft 24 andbutterfly disk 22 shift in position and potentially hinder the operationof the valve.

Optionally, as shown in FIG. 1, the axial end 30 of the shaft 24 mayinclude a plug 52 that is mounted in the axial end 30 for contact withthe wear-resistant coating 40. The plug 52 may be formed of a hardmaterial that resists wear.

In the illustrated example, the thrust plate 32 also includes aplurality of mounts 52 for securing the thrust plate 32 to the valvehousing 21. In embodiments, the thrust plate 32 includes three suchmounts 52 that are uniformly spaced around the periphery of the thrustplate 32. As an example, each of the mounts 52 includes an opening 54therein for receiving a bolt 56 (FIG. 1) to secure the thrust plate 32to the valve housing 21.

Although a combination of features is shown in the illustrated examples,not all of them need to be combined to realize the benefits of variousembodiments of this disclosure. In other words, a system designedaccording to an embodiment of this disclosure will not necessarilyinclude all of the features shown in any one of the Figures or all ofthe portions schematically shown in the Figures. Moreover, selectedfeatures of one example embodiment may be combined with selectedfeatures of other example embodiments.

The preceding description is exemplary rather than limiting in nature.Variations and modifications to the disclosed examples may becomeapparent to those skilled in the art that do not necessarily depart fromthe essence of this disclosure. The scope of legal protection given tothis disclosure can only be determined by studying the following claims.

What is claimed is:
 1. A thrust plate for a butterfly valve, the thrustplate comprising: a thrust plate body defining a recess that extendsbetween a bottom thrust surface, side walls, and an open top; and anickel-based or cobalt-based wear-resistant coating located on thebottom thrust surface, the wear-resistant coating being harder than thethrust plate body.
 2. The thrust plate as recited in claim 1, whereinthe wear-resistant coating is a nickel-based alloy.
 3. The thrust plateas recited in claim 1, wherein the wear-resistant coating includeschromium boride.
 4. The thrust plate as recited in claim 1, wherein thewear-resistant coating includes chromium carbide.
 5. The thrust plate asrecited in claim 1, wherein the thrust plate body is stainless steel. 6.The thrust plate as recited in claim 5, wherein a ratio of a hardness ofthe wear-resistant coating to a hardness of the stainless steel is atleast 2.3.
 7. The thrust plate as recited in claim 6, wherein the recessdefines a recess diameter (RD1) and the wear-resistant coating definesan average coating thickness (CT), and ratio RD1/CT is between 33.2 and56.67.
 8. The thrust plate as recited in claim 7, wherein the recessdefines a recess depth (RD2) and the wear-resistant coating defines anaverage coating thickness (CT), and a ratio RD2/CT is between 5 and10.33.
 9. The thrust plate as recited in claim 8, wherein the thrustplate body, with the exception of the bottom thrust surface, is free ofthe wear-resistant coating.
 10. The thrust plate as recited in claim 1,wherein the thrust plate body is a material selected from a groupconsisting of nickel-based alloy, cobalt-based alloy and steel, and thewear-resistant coating is a nickel-based alloy.
 11. A butterfly valvecomprising: a valve housing defining a flow passage there through; ashaft extending in the valve housing and including a butterfly diskmounted thereon within the flow passage; a thrust plate including athrust plate body defining a recess that receives an end of the shaft,and the recess extends between a bottom thrust surface, side walls, andan open top; and a wear-resistant coating located on the bottom thrustsurface.
 12. The butterfly valve as recited in claim 11, wherein thewear-resistant coating consists essentially of 0.5-1.0 wt. % carbon,12-18 wt. % chromium, 2.5-4.5 wt. % boron, 3.5-5.5 wt. % silicon,3.5-5.5 wt. % iron, up to 0.2 wt. % cobalt, and a remainder of nickel13. The butterfly valve as recited in claim 11, wherein the thrust platebody is stainless steel.
 14. The butterfly valve as recited in claim 13,wherein a ratio of a hardness of the wear-resistant coating to ahardness of the stainless steel is at least 2.3.
 15. The butterfly valveas recited in claim 14, wherein the recess defines a recess diameter(RD1) and the wear-resistant coating defines an average coatingthickness (CT), and ratio RD1/CT is between 33.2 and 56.67.
 16. Thebutterfly valve as recited in claim 15, wherein the recess defines arecess depth (RD2) and the wear-resistant coating defines an averagecoating thickness (CT), and a ratio RD2/CT is between 5 and 10.33. 17.The butterfly valve as recited in claim 16, wherein the thrust platebody, with the exception of the bottom thrust surface, is free of thewear-resistant coating.
 18. The butterfly valve as recited in claim 11,wherein the flow passage defines a central axis, and a long axis of theshaft is non-perpendicular to the central axis.
 19. The butterfly valveas recited in claim 11, wherein the recess defines a recess diameter(RD1) and a recess depth (RD2) and the wear-resistant coating defines anaverage coating thickness (CT) such that a ratio RD1/CT is between 33.2and 56.67 and a ratio RD2/CT is between 5 and 10.33.
 20. A method ofinstalling a thrust plate on a butterfly valve, the method comprising:securing a thrust plate to a valve housing that defines a flow passagethere through such that an end of a shaft, which extends within thevalve housing and includes a butterfly disk mounted thereon, is receivedinto a recess of the thrust plate body, the recess extends between abottom thrust surface, side walls, and an open top, and the bottomthrust surface includes a wear-resistant coating thereon.